Method of adding new feed elements other than hacking parser_simplepie.module?

This may be an obvious question, but here goes nothing:
I would like to add new feed elements - i.e. . I have found the easiest way to do this is just to hack parser_simpliepie.module, by adding the new element to the $curr_item loop (i.e. $curr_item->new_element_name = $value; )

Is there a better "best-practice" method of doing this?
Thanks